The specific aim of this work is to develop a technological means to improve the reliability of counting instruments and other items used in surgical operations. This work will directly result in improved clinical outcomes by reducing or eliminating the occurrence of retained foreign bodies following surgery. The inadvertent retention of a foreign body such as a surgical instrument in a patient's body cavity or incision following a surgical procedure continues to be a dangerous and costly accident. Counting is an error-prone process that can be affected by increasing stress and confusion levels that may occur in emergencies or unplanned changes in the surgical procedure. It is hypothesized that an Automatic Counting System would add a level of security beyond that provided by human counting alone. In Phase I, we will determine the feasibility of several candidate-counting technologies for reducing errors. The candidate technologies are computer-vision, radiofrequency-identification tagging and precision weighing of items used in the surgical operation. The Phase I work will be in two parts. The first part is the experimental measurement of the error rates of the individual candidate technologies in terms of identifying and counting surgical instruments and other items used in operations. The second part is a computer simulation using probabilistic methods applied to a mathematical model of the Automatic Counting System that incorporates the candidate technologies. The simulation will be used to determine how well these candidate technologies perform at reducing overall errors when integrated into the whole system. In Phase II, we will continue this work to arrive at a commercially available and clinically usable product. [unreadable] [unreadable]